Marvel's Sheeva Plug Computer uses 2 watts of power and the processor speed can be up to 2gh for $99 online at the mp3Car Store. It is ideal for a developer and many mp3Car Forum developers have already created software to use with it.
Video over usb is useful if you want to extend digital video. It takes a usb mini input and outputs DVI up to 1080p all for $60. There is also a VGA version. The docking station will give via usb 1080p, DVI, VGA , Ethernet, microphone in, and daisy chain up to 4 usb monitors. Extend 15' or more over one usb cable.